JPS6224725Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a valve train for a multi-valve internal combustion engine, in particular, the biasing force of a spring that elastically supports a valve bridge is increased or decreased in accordance with the lubricating oil pressure. This is intended to facilitate clearance adjustment.

Among internal combustion engines such as diesel engines,
In particular, in multi-valve engines such as three-valve engines with two intake valves and one exhaust valve, or four-valve engines with two intake and exhaust valves, it is necessary to open and close multiple valves at the same time. A valve operating device is provided in which an integrated valve bridge that abuts the head of the valve is provided so as to be able to slide up and down along a guide rod erected on the upper surface of the cylinder head, and the valve arm is pressed to open and close the valve via the valve bridge. However, in this type of valve train, the increase in the inertial mass of the valve train due to the use of the valve bridge causes valve jumping and bouncing, which not only causes rapid wear of the valves and cams, but also increases the inertia of the valve train. There was a problem in that due to the uneven force of each valve spring, twisting occurred between the valve bridge and the guide rod, and the followability of the valve bridge at high speeds deteriorated.

Therefore, the present applicant aims to improve the followability of the valve train in the conventional multi-valve engine and to prevent valve jumping and bouncing, etc.
In Utility Model Application No. 55-168073, it was proposed to attach a cylindrical coil spring to the lower part of the valve bridge to push up the valve bridge.

However, even in the improved valve train having such a configuration, the biasing force of the cylindrical coil spring is set in accordance with the mounting load required during engine operation, and when the engine is assembled or stopped, the biasing force shown in FIG. The valve bridge 1 is now slightly floating.
Since gaps h and h' are created between the heads 2' and 3' of the valves 2 and 3, the amount of threading of the adjustment bolt 4 screwed onto the valve bridge 1 is adjusted to adjust the amount of the valve head. When adjusting the height balance of the parts 2', 3' or the valve clearance between the valves 2, 3 and the valve arm 5, the valve bridge 1 is moved against the biasing force of the cylindrical coil spring 6 each time. Subsequently, it was discovered that there was a drawback in that it was necessary to hold the skimmer cage and tools in hand at the same time while pushing down, making fine adjustments, making these adjustment operations extremely complicated and difficult.

The present invention focuses on the problem of difficulty in adjusting valve clearance, which was present in the valve train proposed earlier by the applicant, and removes the biasing force of the cylindrical coil spring when the engine is stopped, thereby preventing the valve bridge from floating. The valve bridge is installed between the top surface of the cylinder head and the lower part of the valve bridge, which moves up and down along a guide rod installed on the top surface of the cylinder head. In a valve operating system for a multi-valve internal combustion engine in which a cylindrical coil spring for upward biasing is provided, a recess is formed at the base of the guide rod on the upper surface of the cylinder head, and a recess is formed in the recess in response to an increase or decrease in lubricating oil pressure. The present invention is characterized by a structure in which a vertically movable spring receiving member is fitted and accommodated, and the lower end of the cylindrical coil spring is supported by the spring receiving member.

The present invention will be described in more detail below with reference to the embodiments shown in the accompanying drawings.

Fig. 2 shows a cross section of the valve train of the present invention, and in the figure, 11 is a cylinder head, 12
13 is a valve arm shaft supported by a valve arm support (not shown) fixed to the upper surface of the cylinder head 11;
is a valve arm slidably supported by the valve arm shaft 12, and the valve arm 13 has one arm portion 13a.
The adjusting bolt 14 screwed into the valve bridge 17 is engaged with the head of the push rod 15 that moves up and down, and the pressing part 16 formed at the tip of the other arm part 13b is connected to the stopper 18 provided at the top of the valve bridge 17. They are facing each other.

The valve bridge 17 has a guide hole 20 bored in its center, through which a guide rod 19 erected on the upper surface of the cylinder head 11 is inserted, so that it can slide along the length of the guide rod 19. At the same time, a contact portion 21 formed on the lower surface of one arm 17a is engaged with a head 23 on the valve 22 side, and the lower end of an adjustment bolt 24 screwed onto the other arm 17b is connected to the valve 22. 25 side, and when pressed downward by the pressing part 16 of the valve arm 13, it slides downward and closes both valves 2.
2 and 25 are opened at the same time.

The valves 22 and 25 are inserted into center holes of a valve guide 27 that vertically passes through the cylinder head 11, respectively, and a valve head 2 is inserted into each of the valve heads 23 and 26.
Valve spring retainers 29, 29 fixed at 8 and the spring receiving portion 3 formed on the upper surface of the cylinder head 11
The valve springs 31 and 31 are compressed between the valves 0 and 30 and are always biased in the closing direction, that is, upward.

In the valve train having the above configuration, a recess 33 is formed at the base of the guide rod 19 to introduce a portion of the lubricating oil supplied to the valve arm shaft 12 through the oil hole 32. A spring receiving member 34 is slidably inserted through a packing 35.

The spring receiving member 34 has a center hole 34a in the center thereof through which the guide rod 19 is inserted.
An O-ring packing 36 is interposed between the inner periphery of the guide rod 4a and the outer periphery of the guide rod 19, and the upper surface 34b of the O-ring packing 36 and the stepped portion 3 of the valve bridge 17
A cylindrical coil spring 38 is interposed between the
Furthermore, the upper limit movement position of the guide rod 19 is regulated by a retaining ring 39 fitted around the outer periphery of the intermediate portion of the guide rod 19.

The length and elasticity of the cylindrical coil spring 38 are such that the spring receiving member 34 is located at the upper limit due to an increase in lubricating oil pressure in the recess 33, and the upper surface 34b of the spring receiving member 34 and the stepped portion of the valve bridge 17 It is set in advance so that when the spring receiving member 34 is compressed to the distance H from the spring receiving member 37, a predetermined mounting load is exhibited, and when the spring receiving member 34 is lowered as the lubricating oil pressure decreases, it is at least in a non-loaded state.

In the figure, reference numeral 40 indicates a valve arm bonnet attached to cover the upper part of the cylinder head 11, and reference numerals 41 and 42 indicate rotation prevention nuts screwed onto the upper ends of the adjuster bolt 14 and adjustment bolt 24, respectively.

The valve train of the present invention has the above-mentioned configuration. Next, its operation will be explained. First, when the engine is operating, the lubricating oil pump is driven.
When lubricating oil is press-fitted into the recess 33 through the oil hole 32, the spring receiving member 34 is raised by the oil pressure in the recess 33 to the upper limit position where it contacts the retaining ring 39, and the cylindrical coil spring 38 is held at a predetermined position. Valve bridge 1 is compressed until a mounting load is generated.
Since the center part of valve 7 is pushed up and elastically supported by the cylindrical coil spring 38, it can smoothly move up and down as the valve arm 13 swings without twisting between it and the guide rod 19. Then, the valves 22 and 25 are opened and closed.

On the other hand, when the engine is stopped or assembled, if the lubricating oil pump is stopped and there is no trace of hydraulic pressure being supplied to the recess 33, the spring receiving member 34 is lowered and the cylindrical coil spring 38 is released. Due to the loaded state, the valve bridge 17 has been lowered by its own weight to a position where it abuts the valves 22 and 25.

Therefore, when adjusting the balance between the heights of the valves 22 and 25, it can be easily done by simply loosening the locking nut 42 and adjusting the screwing amount of the adjusting bolt 24. When adjusting the gap between the fitting 18 and the pressing part 16 of the valve arm 13, that is, adjusting the valve clearance, insert a feeler gauge into the part and tighten the adjuster bolt 14.
This can be easily done by one worker by adjusting the amount of screwing in.

As described above, the valve train of the present invention is a valve train for a multi-valve internal combustion engine in which a cylindrical coil spring provided at the bottom of a valve bridge elastically supports the valve bridge. The cylindrical coil spring is supported by a spring support member that moves up and down as the lubricating oil pressure increases and decreases, and when the engine is running, the cylindrical coil spring has a predetermined mounting load, and when the engine is stopped, the biasing force of the cylindrical coil spring on the valve bridge is removed. The valve bridge is lowered by its own weight and engages with the valve head of the valve, so when adjusting the valve clearance, there is no need to hold the valve bridge as in conventional valve gears, and the adjustment is easy. This is extremely easy and efficient, and during engine operation, the floating action of the valve bridge by the cylindrical coil spring and the elasticity compensating action of the valve spring smooth the movement of the valve bridge and follow the valve train even under high-speed operation. It has an excellent effect of causing

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional valve train;
FIG. 2 is a sectional view showing an example of the valve train of the present invention. 11... Cylinder head, 17... Valve bridge, 19... Guide rod, 33... Recess, 3
4... Spring receiving member, 38... Cylindrical coil spring.

Claims (1)

[Scope of utility model registration request] A multi-valve internal combustion engine has a cylindrical coil spring interposed between the upper surface of the cylinder head and the lower part of the valve bridge that moves up and down along a guide rod erected on the upper surface of the cylinder head to push up and bias the valve bridge. In the valve train, a recess is formed at the base of the guide rod on the upper surface of the cylinder head, and a spring receiving member that moves up and down in response to increases and decreases in lubricating oil pressure is fitted and housed in the recess;
A valve operating system for a multi-valve internal combustion engine, characterized in that a lower end of the cylindrical coil spring is supported by the spring receiving member.